The present invention relates generally to wireless communications, and more particularly, to monitoring the wireless link status of multiple wireless communication units to determine a reason for link degradation.
In some cases, medical device systems for disease management include sensor devices, medication delivery devices, processors, and/or control devices that operate together to assist a patient in maintaining healthier physiological processes. For example, in an integrated diabetes mellitus management (IDM) system, a sensor is attached at one position on a patient's body for the purpose of sensing the patient's glucose and providing a measurement signal representative thereof. An insulin pump is attached at a second position on a patient's body for the purpose of delivering programmed amounts of insulin to the patient for closely controlling the patient's glucose level. A third device, a controller, is typically a hand-held device that is configured to receive the glucose measurement signal, analyze it, and display a recommended dose of insulin to the patient. The patient may then control the insulin pump to deliver that recommended dose. In some cases, the delivery pump is configured to provide data signals regarding past and ongoing medication deliveries and the controller is also programmed to analyze such pump delivery data signals in determining the recommended dose of insulin provided to the patient.
Depending on the user, receipt and analysis of such sensor and pump data may need to occur on a continuous basis to avoid user health problems. For example, a user with diabetes should continually receive such data to be able to take steps to avoid a hypoglycemic or hyperglycemic condition, both of which can have serious consequences for the health of the user.
With the availability of low cost wireless technology, integrated systems such as that discussed above become more convenient and acceptable in that wires are not needed to interconnect the devices. Not only are wires burdensome to handle with on-body medical devices, but many users desire to keep their medical affliction confidential, which is more difficult to accomplish when wires exist. Each of the devices of the integrated system may incorporate a wireless communication module that allows it to communicate with at least one other device that uses a wireless link. In some cases, the communication module of the device may be a transceiver, but in other cases, it may simply be a receiver or a transmitter, depending on the function of the device.
Another important consideration with wireless radio frequency (RF) devices is their reliance on battery power. As is well known, transmitters typically tend to use far more battery power than receivers use. Different types of transmitting protocols may be employed that use less power, such as burst transmission, or periodic transmission, as opposed to continuous transmission. Nevertheless, battery power is still required and overuse of battery power can cause the premature expiration of the battery with the resulting requirement that the battery in the subsystem be replaced, or the entire device replaced. In an IDM system such as that discussed above, premature replacement of either the battery or the device itself is highly undesirable due to the necessary skin punctures that are required.
Referring now to FIG. 1, an IDM system 48 is shown. A glucose sensor 54 provides glucose signals while the pump 64 provides medication delivery data and pump status (such as programming) signals. Should both devices wirelessly transmit their data simultaneously, interference may result and the data may be lost since a receiver 70 may not reliably be able to discern between the two. One method of avoiding interference between the two is to use two different frequencies. In the embodiment shown in FIG. 1, the sensor-to-controller wireless RF link 50 would be a first subsystem 52 operating on a first frequency f1 while the pump-to-controller wireless RF link 60 would be a second subsystem 62 operating on a second frequency f2, that is different from the first frequency.
An example of a medical system using multiple frequencies in its subsystems is the integrated diabetes management (IDM) system being discussed and shown in FIG. 1. In one embodiment, the glucose sensor device 54 operates on 433 MHz, which is f1. The insulin delivery pump 64 operates on 2.4 GHz, which is f2. Due to the large difference between these two subsystem frequencies, interference is unlikely and better data communication is achieved. However, poor radio performance can nevertheless occur.
In the past, a radio subsystem that detects the existence of a degraded wireless link would increase the transmitting power to try to establish and maintain communications. However, this will have the effect of faster depletion of the battery as discussed above and may make the premature replacement of a device undesirably necessary. Maintaining a lower use of battery power to prolong the battery life of the devices is highly desired.
In prior systems, if the radio performance was degraded below a usability threshold, the user was informed and given general guidance to resolve the problem. Such general guidance may have taken the form of asking the user to determine general conditions of a device, such as checking that a switch is in the “on” position, or to check the batteries for viability, both of which are things that most users would have already considered. Other, more specific guidance was not provided, and present systems are unable to provide helpful information or guidance specifically regarding resolution of wireless communication issues when radio performance is degraded. Existing controllers, for example, typically instruct transmitter modules to switch to a continuous transmission mode in an attempt to establish a usable wireless link, or to increase the power level of transmission, both of which are undesirable if they are not absolutely needed. Other systems simply advise a user that a communication problem exists and that manual glucose testing, calculation, and pump analysis should be performed. The above techniques can result in considerable user inconvenience and anxiety, especially if the reason for the communication link degradation is easily correctable.
Hence, those skilled in the art have recognized the need for a system that is able to provide better guidance for correcting wireless communication problems without invoking the excessive use of battery power. A need has also been recognized for devices and systems that can provide improved diagnosis of wireless communication link problems and that can provide guidance that is more specific to users regarding correction of wireless communication problems between medical devices. The invention fulfills these needs and others.